Summer in Slovakia is no longer just about a few hot days in July. Tropical nights, temperatures above 35°C and rising energy bills are turning air conditioning from a luxury into a standard household feature—much like washing machines and dishwashers once were. The problem is that the market is saturated with options, and without understanding a few basic parameters, it is easy to buy a unit that is either unnecessarily oversized or unable to cool the space effectively.
This guide explains what you should really consider when choosing an air conditioner—from cooling capacity and noise levels to the differences between solutions for apartments and detached houses.
How much cooling capacity does your room really need?
This is where most mistakes are made. A salesperson may recommend a more powerful unit “just to make sure it is enough,” but the result can be a system that constantly switches on and off instead of running smoothly at a low output—increasing both energy consumption and noise.
A basic rule of thumb is to allow approximately 1 kW of cooling capacity per 10 m² of floor area with a standard ceiling height of 2.6–2.7 metres. This gives the following general recommendations:
- up to 25 m² (bedroom, small home office or child’s room) → sufficient capacity: 2.5 kW air conditioners
- 25–35 m² (apartment living room or office) → a better choice: 3.5 kW air conditioners
- over 45 m² (open-plan living space or larger office) → 5 kW or more, or a multi-split system
Add another 10–20% to these estimates if:
- you have large south- or west-facing windows,
- you live directly below the roof or in an attic apartment,
- the room contains a lot of electronic equipment, such as several computers or a gaming setup,
- it is a new-build property with extensive glazing that is prone to overheating.
The required capacity can be calculated more precisely by accounting for factors such as heat loss, building orientation and the number of occupants. For an average household, however, this estimate provides a sufficiently accurate basis for making a decision.
Decibels matter more than you might expect
While most people have at least a general idea of what cooling capacity means, noise levels are routinely underestimated. Yet noise is precisely what determines whether you will appreciate having a unit in your bedroom or find it irritating after three weeks.
Use the following scale as a guide:
- 19–22 dB — units this quiet are practically inaudible, making them ideal for bedrooms and children’s rooms
- 25–35 dB — the normal range for most high-quality split units and suitable for living rooms
- over 50 dB — typical of cheaper portable air conditioners, which are not recommended for bedrooms
Do not overlook the outdoor unit either. In densely populated residential areas, its noise level can affect relations with your neighbours just as much as it affects your own comfort.
What to ask the salesperson in 2026
The market has advanced considerably in the past few years. If you want a system that will last and will not unnecessarily increase your electricity bills, focus on the following points:
Inverter technology. This is now standard equipment, not an optional extra. By continuously regulating output, an inverter can save around 30% of the energy used by an older, non-inverter unit.
App-based controls. This is a practical feature, not a gimmick—you can switch on the cooling while travelling home from work and arrive to a cool interior instead of waiting 20 minutes after you get home.
Air filtration. HEPA and plasma filters capture dust, pollen, bacteria and viruses. For people with allergies, this is now one of the main reasons for considering air conditioning in the first place.
R32 refrigerant. In 2026, this environmentally friendlier refrigerant is the established standard. It has a lower environmental impact and offers better energy efficiency than older refrigerant types.
Apartment or house: different conditions require different solutions
The most common solution for an apartment is a conventional split system with one indoor and one outdoor unit. If you want to cool several rooms at the same time, a multi-split system is an option. It connects multiple indoor units to a single outdoor unit, saving façade space and reducing installation costs compared with several separate systems.
In a detached house, you have a wider range of options:
- wall-mounted units — the most common and affordable solution,
- cassette units — recessed into the ceiling and suitable where you do not want a unit mounted on the wall,
- ducted units — fully concealed above a suspended ceiling, making them the least visually intrusive option.
These options are best considered during the design or renovation stage, as the ductwork and connections must be installed before the suspended ceilings are completed.
Energy class: where the investment really pays off
When comparing offers, check the energy label. A++ and A+++ ratings mean significantly lower consumption than older or cheaper models. With normal use, the price difference between an A-rated and an A+++ unit can often be recouped through lower electricity bills in just one or two seasons.
Final summary
Choosing the right air conditioner comes down to four key factors: the correct capacity for your room, an acceptable noise level, modern features such as an inverter, app controls and filtration, and a high energy-efficiency rating. If you are unsure which type and capacity are best for your space, it is worth having it professionally assessed. This can help you avoid disappointment caused by inadequate cooling as well as unnecessarily high energy bills.
Robert
I’m interested in technology and history, especially true crime stories. For three years I ran a fact-based portal about modern history, and for a year I co-built a blogging platform where I published dozens of analytical articles. I founded offpitch so that quality content wouldn’t be hidden behind a paywall.
